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DESCRIPTION JPS5990498

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DESCRIPTION JPS5990498
[0001]
TECHNICAL FIELD OF THE INVENTION The present invention relates to an ultrasonic probe in
an ultrasonic diagnostic apparatus. [Technical Aspect of the Invention] The ultrasonic probe
converts an electrical signal into an ultrasonic wave and emits it into the living body, and then
receives the ultrasonic wave reflected in the cow body again. Piezoelectric vibrator that acts as a
so-called electric-to-harm converter (transducer) that converts electric signals, current applied to
the electrodes applied on both sides of the piezoelectric vibrator for applying a voltage to the
piezoelectric vibrator, and the WS pole An acoustic reflection layer from the rear surface of the
acoustic lens for focusing ultrasonic waves is eliminated by (1/4) ? acoustic matching layer for
efficiently transmitting and receiving ultrasonic waves to and from the wiring substrate where it
is guided For the rear surface acoustic absorber. For example, piezoelectric ceramic such as PZT
(lead zirconate titanate) is used as the piezoelectric vibrator, double-sided Ti electrodes formed
by vapor deposition or transfer of metal such as silver, 49% plate as a flexible printed board,
copper plate For example, glass or epoxy resin is used as an acoustic matching layer, and rubber
or the like having a large acoustic absorptivity is used as a rear surface acoustic absorber such as
silicon rubber fluorine rubber as an acoustic lens. FIG. 1 shows the structure of an ultrasonic
wave tentacle. 1 is a piezoelectric vibrator, 2 is an electrode coated on the surface of the vibrator,
3.3 'is a substrate and metal electrode, 4 is an acoustic matching layer, 5 is an acoustic lens, and
6 is a rear surface acoustic absorbing material. When manufacturing a conventional vibrator, for
example, as shown in Japanese Patent Publication No. 55-12254 @ (Iinuma, plate material), the
connection between the electrode on the surface of the vibrator and the wiring board and the
metal electrode should be soldered on the vibrator surface. It was done by. On the surface of the
vibrator 10? Since t2 poles 2 and 2 'are applied as shown in FIG. 2, the printed circuit board and
metal electrode 3.3' are soldered to the soldered portions 12 and 12 '. The electrodes on the
surface of the vibrator have such a structure in order to solder on the front surface of the
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vibrator (that is, on the side of the acoustic matching layer) for both the signal line and the
ground line. The vibrators to which the electrodes are soldered are adhered to the back surface
acoustic absorber 6 with an adhesive, and then cut into pieces so as to match the electrode
patterns of the printed circuit board. [Problems of the Related Art] In the case of (1) above, when
soldering () the electrodes on the surface of the vibrator, the human hand applies the soldering
iron in order from * i: of the vibrator, so the vibrator But it is very easy to warp due to heating,
and sometimes it may be several millimeters. When the transducer is smoothed, when bonding
the rear surface acoustic absorber, Ij will be added to the warp and the tongue will be added in
the reverse direction, so the transducer is very likely to be broken.
When the thickness frequency of the vibrator is increased, the vibrator becomes thinner and the
distortion also increases. In addition, since the flexible pull-printed substrate used as the wiring
substrate is also heated together, the bulged surface due to heat may be misaligned when cutting
the vibrator at the same time. There are many. Furthermore, as shown in FIG. 2 J: Since a rotating
electrode is used so that the electric wire is not connected to the acoustic matching layer side,
the effective visual field width W 'of the S motion is more than the actual S motion width W
Becomes smaller. Assuming that the wavelength of the ultrahigh wave is ?, the beam width of
the ultrasonic wave depends on ? / W ', and therefore, for the same ultrasonic frequency, the
smaller the effective field width W', the wider the beam width will be. . Further, since the power
source impedance of the pulsar transmission system is about several ohms to about several
ohms, it is ideal that the impedance Z of the vibrator is also about several ohms to about several
ohms. This impedance 7 appears as shown in the following equation. 1Zl = l / j?C0 = 1 / j??S
= l / j??DW '(1) where CO is the electric capacitance of the oscillator, ? is the permittivity of
the oscillator, and S is the oscillator. The radiation area (S = W ? О D) D is the visual field width
in the scanning direction, and 1 is the transducer thickness. At present, the impedance of the
vibrator is much higher than the power supply impedance (about 100 ?). It is better to reduce
the impedance of the vibrator as much as possible. However, the smaller the W ', the larger the
impedance of the vibrator. Mismatching with the impedance is large and the transmission power
of the ultrasonic wave is small. [Object of the invention] The present invention has been made in
view of the above-mentioned point, and it is difficult for a warp of a vibrator to occur during a
manufacturing process, and furthermore, a Jf1 sound wave probe which can obtain one large
transmission power. Intended to be provided. In order to achieve this object, the present
invention provides a rectangular parallelepiped shaped piezoelectric vibrator which mechanically
vibrates by applying snow pressure, a first electrode provided on the front and the side of the
vibrator, and the first electrode. And a plurality of vibrators provided with the second electrode
and the first and second electrodes provided on the bearing surface and the side surface of the
vibrator so as to face the first electrode. It is characterized in that it comprises the back surface
acoustic absorber and the first and second electrode lead terminals in which the first Ti pole and
the second electrode are respectively connected by conducting wires on the side surface of the
vibrator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the
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present invention will be described below with reference to the drawings. In this embodiment, as
shown in the front view of FIG. 3, the electrodes 21 provided on the front and the side of the
piezoelectric vibrator 11 and the back and the side of the vibrator 11 facing the electrode 21
were provided. Electrode 22 and this?
It comprises a back surface acoustic absorber 61 on which a plurality of vibrators 11 provided
with v2 poles 21.22 are fixed, and electrode lead wires 31.32 connected with the respective
electrodes 21.22 and leads 33, 6-34. This embodiment is manufactured as follows. First, the
piezoelectric vibrator 11 to which the electrode 21. 22 is applied is bonded to the rear surface
acoustic absorbing material 61 without soldering the electrode lead wire 31. 32, and then the
vibrator 11 is cut into small pieces. (A substance such as gold is preferable as the electrode
applied to the surface of the vibrator) This is cut at a bit of about 0.20 to 0.30 mm as in the prior
art. (The cutting pitch is paid by the thickness vibration frequency of the vibrator used). Next, the
electrode lead wire 31.32 is bonded to the side surface of the back surface acoustic absorber 61.
As the electrode lead wire, a flexible pudding 1-substrate or metal electrode as conventionally
used may be used, or adhesion with the rear surface acoustic absorber becomes easy. J: The back
side of the electrode lead wire has a smooth surface It may be covered with polished ones. After
that, wire bonding is performed as shown in FIG. Several pieces of the finely cut vibrators 11 are
put together (to be referred to as ?N?. Normally N = 3 to 6) Since it is connected to the
electrode 1ch, first, scanning is performed sideways at the cutting pitch d of the vibrator 11 to
perform wire bonding. Next, wire bonding is performed by vertically scanning the electrode 31
(flexible printed circuit board) lch from 1) of N]. At this time, any one of N transducers may be
selected as the vibrator 11 connected to the electrode 35. The vibrator 11 may be connected to
the whole power 1f + 35, but in the electrode pattern, the electrode exposed portion (for
example, a gold-plated copper plate) must be enlarged. The above operation is the number of
channels of the electrode. As shown in FIG. 4B on the earth electrode side, the Ti pole extraction
1a! After bonding 32 to the rear surface acoustic absorbing material 61 and then cutting all the
imaging moving elements 11 by scanning them horizontally and connecting them by wire
bonding, and further connecting 1 or more of the transducers longitudinally by wire bonding
Connect to 1 tili 717 pole 36 gold. When performing this work, if the electrode side (ie, the
printed circuit board side) is on the opposite side and you intend to perform wire bonding on the
other side with the weir facing down already with the wire bonding work downward, An
excessive force is applied to the wire-bonded electrode surface. Furthermore, it is difficult
because the parallelism of the surface to be wire-bonded on the opposite surface can not be
obtained.
For this reason, when performing wire bonding on the opposite surface (ie, the ground electrode
surface), as shown in FIG. 5, the ultrasonic probe is performed so that the rear surface 28 after
molding the surface 28 already wire bonded does not contact downward. Wire bonding is
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performed on the opposite surface 29 so as to support the child 10. As a method of supporting
the ultrasonic probe 10, pressure may be applied from both sides of the side surface of the rear
surface acoustic absorbing material 61 or a material that hooks on the side surface may be
adhered. The series of wire bondings can be automatically performed only by the initial setting,
and the electrical connection to the vibrator can be performed automatically and accurately. With
regard to heating, wire bonding also seems to have a certain degree of heating (one hundred and
several tens of degrees C), but it is considered to be that 9 = soldered solder partially heats the
vibrator. In the case of wire bonding, the warp and thermal expansion of the vibrator can be
ignored because the imaging actuator 11 has already been finely cut during heating A and
heating. When soldering on a flexible printed circuit board, the front end of the printed circuit
board is printed on both sides as shown in FIG. 6A. j (copper) was exposed and it was very easy
to expand when heated because all the electrodes were connected so as to facilitate soldering,
but in the present invention, it is shown in FIG. 6B. As described above, the base 31 is covered
and fixed to the back surface of the electrode portion 35, and the Ti electrode portion of the front
surface is completely separated, so that the expansion of copper can be suppressed to almost
negligible. A hatched portion 40 is a gap for dividing the channel. As for the size of one section to
be wire-bonded on the side surface of the vibrator, in the case of a PZT vibrator having a
thickness vibration frequency of 5 M l-1z, the vibrator thickness is about 0.3 to 0.4 mm and the
cutting bit 0.2 to 0. Although it is 25 mm, it can be said that the size of the wire 10 is small to
perform bonding. The transducer with the wire bond is coated with the acoustic matching layer
and then attached to the probe case, but the wire is very easy to be broken, so it needs to be
molded to protect it. As a method of molding, for example, there is a method of pouring in and
hardening an epoxy resin such as araldite. Since the aralgate has a low viscosity, it does not
affect the connection when it is poured. In order to prevent leakage of the araldite by pouring in
and to maintain the parallelism of the wire bonding bar of the transducer and the back surface
acoustic absorbing material, bonding is performed after the wire bonding is completed as shown
in FIG. 7 ? and B. The case 41 may be adhered so as to cover the portion, and the resin may be
poured from the upper side.
FIG. 7A is a side view of the vibrator, and FIG. 7B is a front view of the vibrator. After bonding the
case 41 so as to cover the wire bonding portion, a molding agent is poured into this gap. At this
time, it is necessary to pull out the printed circuit board or metal electrodes 31 and 32 to the
outside for bonding the case to the 61 port, but this is the case name on the protective film
(polyimide etc.) of the printed i-substrate or metal surface. do it. Finally, the above case is
attached to the probe case. In order to perform this wiring, it is necessary to apply J: U 'Fi pole
shown in FIG. 3 to the surface of the vibrator, but in this case, only part of the soldering is lost.
The emission surface of the ultrasound can be made large as compared to the structure shown in
FIG. It is known that the minimum beam width of ultrasonic waves depends on ? / W when
focusing J: ultrasonic waves on an RP lens or the like. (? is the wavelength of the ultrasonic
wave, W is the field width of the transducer) Conventionally, since the width required for adding
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the rapid opening 1 is about 3 mm, in the case of the transducer shape of the conventional field
width 5 mm Since the field of view width 8I11m can be made, the minimum beam width can be
made about 0.6 times. On the contrary, in order to obtain a transducer having a field of view
width of 5 mm, the transducer width of 9 mm is conventionally required, whereas in the present
method, the transducer width of 6 mm is sufficient. The transducer width is wide (1 mm in the
gap between the electrodes) (If the radiation pressure of the ultrasonic wave is constant, the
transmission power is increased by the increase in the area. That is, the radiation power P of the
ultrasonic wave is Pm5 (S is the effective vibration area of the transducer). Also, according to the
conventional electrode structure, asymmetry of the sound field occurs in the width direction of
the vibrator and the side lobes become large, but according to the method of the present
invention, the sound field is symmetrical and the side lobes should be minimized. It is. Further,
the impedance Z of the vibrator is expressed by the above-mentioned equation (1). The electrical
energy supplied from the power supply to the vibrator is given by the following equation. Pm [Z /
(Z + R)] и VR is the power supply impedance, ? is the power supply voltage. For example, if W =
5 n + n + and Z-50 ?, then R = 100 (this value is considered to be close to the actual value) PmO,
014 V, but according to this method W = 8 mm. It becomes -31 ohms and Pm becomes 0.019V,
and the sensitivity rises by about 30%. This effect becomes more pronounced as the transducer
becomes smaller. These two effects produced by widening the effective field width indicate that
further miniaturization can be achieved in the width direction of the transducer.
As described above, according to the present invention, the electrode connection by soldering is
eliminated by performing wire bonding on the side surface of the vibrator, the warp of the
vibrator, and the pattern deviation due to the thermal expansion of the flexible printed board are
eliminated and the bonding portion is molded. To protect the electrode section and effectively
use the transducer surface as an ultrasonic wave emitting surface, and it is possible to achieve
effects such as power-up of the transmission sound wave, increase of the ultrasonic focusing
degree, and reduction of side lobes. it can.
[0002]
Brief description of the drawings
[0003]
1 and 2 show the structure of a conventional ultrasonic probe, and FIGS. 3, 4 and 5 show the
structure of an embodiment of the present invention, and FIG. FIG. 7 is a diagram showing a
method of molding.
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= 14-10 иииииииииииииииииииииииииииииииииииииииииииииииииииииииииииии Electrodes 31.32 ииииии? ? ? ? ? ? ? ? ? ? ? ? ?
??????????????????????????????????
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?(Other
one person) 15-Fig. 1 N Fig. 2
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